United States' Manteo Mitchell competes in a 4x400-meter relay heat during the athletics in the Olympic Stadium at the 2012 Summer Olympics, in London on Thursday. Manteo had half a lap to go in the first leg of the 4x400-meter relay preliminaries when he broke his leg, and was faced with a choice: keep running or stop and lose the race.

By Lisa Flam

He heard the break. He felt the pain. And he just wanted to lie down.

But after he broke his leg during the semifinal round of the men’s Olympic 4 x 400 meter relay on Thursday, sprinter Manteo Mitchell kept on running, even though, he said, “It felt like somebody literally just snapped my leg in half.”

“It’s impressive both because he’s dealing with pain as well as not having all of his parts in an optimal situation,” says Dr. Balu Natarajan, a sports medicine specialist in Chicago.

He attributes Mitchell’s feat to a combination of the highly trained athlete’s fight-or-flight response to pain and the fact that the bone he broke in his lower left leg, the fibula, absorbs less shock and does less work than the other leg bones.

“Part of it was that the fibula contributes less to weight bearing as opposed to the femur and tibia and part of it is that in that high-energy situation, he has enough adrenaline and endorphins kicking throughout his body that he’s feeling a lot less pain at that moment,” said Natarajan, who also serves on the medical team of the Chicago Marathon.

Had the 25-year-old Mitchell broken his femur or tibia, it would have been nearly impossible for him to finish the race, he said. If a leg bone had to break, he was in a sense lucky it was the fibula.

“If it’s a short enough distance and a high level enough athlete, even with a broken fibula, someone can finish the race,” Natarajan said.

In a statement released through USA Track & Field, Mitchell said the roar of the crowd was so loud that nobody heard his “little war cry,” and he said he didn’t want to let his teammates down. Mitchell finished his heat in 46.1 seconds, only 1.5 seconds longer than the runner of the next leg; the U.S. qualified for the finals and finished in the fastest time ever run in the first round of the relay at the Olympics. On Friday, the U.S. team went on to win a silver medal, thanks in part to Mitchell's sacrifice.

In a high-stakes event like the Olympics after years of training, athletes sometimes will stop at nothing, experts say.

“There’s so much that’s tied into the psyche during a race like this, it really can override a lot of things we would feel outside of such a high energy situation,” Natarajan said. “If the same thing happened on training run and no one was around, he would very likely have stopped.”

“Anybody who has trained for a particular event for four years, really they have one goal, and between that and the tremendous conditioning and excellent biomechanics, it’s really the perfect confluence of factors that might allow someone to overcome a break like this,” he said.

Mitchell said he had slipped on the stairs a few days earlier, but had it checked out, felt fine and didn't think much of it. Mitchell’s strong finish in the race was a clear example of a top athlete’s ability to put mind over matter, says Frank Smoll, a professor of sport psychology at the University of Washington.

“It’s a very good illustration of how highly motivated they are and their willingness to pursue and persist and play through pain, so that the importance of what they’re doing really outweighs the potential negative consequences, in this case, physical harm,” he said.

“They’re highly dedicated athletes, they’re courageous, and they’re willing to, at their own self-sacrifice, give it their all,” Smoll said.

The training Olympic athletes receive in "attention control," the ability to block out distractions like pain, helps them succeed, Smoll said, adding: “It’s not just the physical ability that makes the elite athletes but the mental preparation is what makes them excel.”

The U.S. men's 4 x 400 relay team won a silver medal on Friday; Mitchell, who has been fitted with a boot and crutches, will receive a medal with the rest of the team.

Mmm, gold medal ... om nom nom. Team USA chomp on their medals after winning the women's team gymnastics final on July 31. From left to right, we have Mckayla Maroney, Kyla Ross, Alexandra Raisman, Gabrielle Douglas and Jordyn Wieber.

After medal-winning Olympians stand on the platform, receive their medals, and solemnly listen to the gold medal winner’s national anthem, they leave the stage and face an army of photographers. In front of the flashing lights, many winners grab their medals and take a bite.

It takes years of grueling training and competition to nab gold at the Olympics. So why do the winners immediately chomp on their hard-earned prizes?

The simple answer: Because the photographers ask them to, says David Wallechinsky, president of the International Society of Olympic Historians and author of “The Complete Book of the Olympics, via email.

While Olympic historians aren’t sure which athlete started the trend, they believe the athletes nibble their prizes to test the metal. People once bit gold coins try to make an indent; a small tooth mark in a coin assured it consisted of real gold, which is more malleable than counterfeit gold-plated lead coins.

“We know that only in 1912 the gold medals were real gold and that in all later Olympics the gold medals were made from silver with a gilt layer to show it as being gold,” explains Tony Bijkerk, secretary-general of the International Society of Olympic Historians via email. The 2012 medals contain 1.34 percent of gold, making it one of the biggest medals.

“Unfortunately, the gold layer sometimes had a tendency to fade over the years. Fanny Blankers-Koen, the heroine of the 1948 Olympics in London, who was a good friend of mine, once told me that she had to have her four gold medals re-gilded two times over the years.” (Blankers-Koen was a 30-year-old mother of two who medaled in running events, helping to prove women could be as athletic as men.)

Even though the medal isn’t solid gold, Bijkerk suspects that Olympians could make a mark in the medal, depending on how hard they bite. And some really sink their teeth into their prizes. At the 2010 Winter Olympics, German luger, David Moeller, who won a silver medal, broke his tooth while mugging for cameras and showing off his bite.

“Sports all have their eccentricities,” says Farley, a professor from Temple University in Philadelphia and former president of the American Psychological Association. “If you want to be part of the winning zeitgeist, that winning culture, you participate in that winning practice.”

But he believes that medal biting is more than Olympians simply acting like winners. “It makes your medals yours,” Farley says. “It’s an emotional connection with your accomplishment.”

And even if the Olympians do indent their medals, it makes the prize individual; bite imprints are as unique as the swirls on our digits.

“The concept of the icon, something representing something else, is pretty deep in all of us. In the Olympics, they have a twist on it; it’s like imprinting [yourself] there for all of time.”

Anthony Quintano / NBC News

Ah, the sweet taste of victory! U.S. swimmer Ricky Berens takes a bite of his gold and silver medals on the TODAY set in London.

Germany's Katrin Holtwick sports kinesio tape during the women's beach volleyball preliminary match against Czech Republic during the London 2012 Olympic Games on July 28.

German beach volleyball player Katrin Holtwick might be more internationally famous for the aquamarine lines of tape trailing down her midriff than her serves and spikes. But the 28-year-old Olympian isn’t making a fashion statement; she’s using the tape to alleviate pain and perform better. In theory, anyway.

Kinesiology tape, or kinesio tape for short, is a flexible, cloth tape, which athletic trainers apply on achy muscles to relieve pain or to encourage muscles to work more efficiently. People specifically trained to apply the tape place it over the muscles in precise ways; the tape exerts force on the muscles so they are more synchronized.

“It’s cotton tape that has some sort of adhesive that mimics the elasticity of the skin,” says Dr. Aaron Mares, an assistant professor of orthopaedic surgery at UPMC Sports Medicine and associate team physician for the University of Pittsburgh football team.

Other notable Olympics tape sightings: Beach volleyball star Kerri Walsh Jennings has taped up her right shoulder, the Chinese synchronized diving pair striped their lower backs with the stuff and every other commercial break there seems to be an ad for the brand of tape called SpiderTech. But aficionados of kinesio tape aren't all elite, Olympic-level athletes -- amateur runners and cyclists, for example, use the stuff, too.

Fans of kinesio tape say it reduces pain by increasing blood flow and encouraging lymphatic drainage. It's also intended to help the muscle work correctly after an injury. Say a beach volleyball player has a sore muscle in her shoulder. She might serve a bit differently because she’s using her other muscles to overcompensate for the tender one. The kinesio tape -- again, in theory -- should reduce the inflammation that causes pain and encourage her muscles to move properly.

“If there is a structural damage like a torn ACL or meniscus, it’s not going to be effective; after all, it’s tape,” explains Dr. David Geier, an orthopaedic surgeon at the Medical University of South Carolina and director of its sports medicine program.

Currently, there is not a lot of research indicating that kinesio tape actually works -- but if athletes believe it helps, that in itself might be enough. It could be an example of the placebo effect, the phenomenon when people feel better after taking a pill, even though it might be inactive. Traditional taping -- such as what’s used for a sprained ankle -- and kinesio tape helps people with proprioception, a person’s perception of where a body part exists in relation to their body. Even just that simple act of re-familiarization with the athlete's own body may help give them the feeling that their body is aligned and whole -- and ready to compete.

“[Kinesio tape] is not something that harms the patients. If athletes feel this may help benefit them from a performance standpoint, I have no problems with them trying it,” says Mares.

U.S. silver medalist gymnast McKayla Maroney makes a face during the podium ceremony for the artistic gymnastics women's vault finals at the 2012 Summer Olympics on Sunday in London.

The look on McKayla Maroney's face seems to say it all.

The U.S. gymnast, considered a lock for a gold medal, slipped during her final vault Sunday, missing the coveted prize by a fraction of a point. While the world champion took home silver, her face seems to succinctly sum up the research of a Cornell psychology professor: coming in at number two feels a little like, well, number two.

"Bronze medalists are one step away from not getting anything," says Thomas Gilovich, who conducted a study of winning Olympic athletes in 1995. "But the silver medalist is one step away from something that's very different -- the winner, the thing that gets you on the Wheaties box."

For his study, Gilovich, who's been at Cornell for 30 years, showed clips of winning medalists from the 1992 Summer Olympic Games in Barcelona to a group of non-sporty subjects, then had them rate how happy the participants looked. One tape showed immediate reactions after the athletes had finished their performance; the other showed them on the podium receiving their medals.

The psychology professor also created another tape of follow-up interviews with silver and bronze medalists and showed them to people for their interpretation.

"There was much more of an 'If only' kind of dialogue on the part of the silver medalists and a 'Well, at least I' dialogue going on with the bronze medalists," he says.

Are bronze medalists actually happier than silver medalists?

Michelle Rohl, a race walker who brought home a silver medal in 1995 and a bronze medal in 1999 from the Pan American Games, says she remembers feeling a bit disappointed with her second place honor.

"Yeah, there was a little bit of kicking myself," she says. "Although it was more later than right away. I kept thinking, 'I could have had that gold. I could have been a gold medalist.'"

Gilovich says when it comes to prizes, our minds are drawn upward when it comes to second place and drawn downward when it comes to third -- and that the results are pretty much universal.

"How the mind works is the same across cultures," he says. "The mind's going to be pulled in one direction disproportionately by virtue of the different payoffs of the gold, silver and bronze."

But as the years go by, people do become more content with their second place wins, Gilovich says.

"We have this great set of mechanisms referred to as the psychological immune system to help us deal with these problems," he says. "I think people do get more comfortable with it over time, however, just losing out on something can be hard to deal with. We have stories about the one that got away -- whether it's fishing or love. I suspect the same thing is true of Olympic medals."

Mark Grimmette, am American luger who took a silver at the 2002 Salt Lake City Olympics and a bronze at the 1998 Nagano Olympics, says time has helped ease his disappointment.

"I had a very long and successful career," he says. "I can't say it's something that grinds me to this day."

The athlete -- currently working as a coach for the United States Luge Association -- says he does occasionally think of his near-miss, though.

"Athletes are analytical," he says. "When I go back and look at those performances, I cringe a little bit at those moments where it could have gone one way or the other. I'll still have that feeling for a long time. But you have to make sure you put it in proper perspective in life."

Rohl, currently the track and field assistant coach at Mansfield University in Mansfield, Penn., may have done just that.

"I wish I would have gotten a gold medal at the Pan Am Games but it's not that important to me anymore," she says. "I actually don't even know where my silver medal is. I'm sure it must be somewhere."